Class 12 CBSE conceptual physics questions for board exams 2025

Board exams are approaching. Here are a few questions to solve 

Question 1. 

what is the amount of work done in moving $100 \; \mu C$ charge between two points 5 cm apart on an equipotential surface?    ( 1)

Question 2. 

What is the value of refractive index of medium of polarizing angle 60 degree?       ( 1)

Question 3. 

State two factors on which temperature of inversion of a thermocouple may depend.             ( 1)

Question 4. 

In which direction would a compass needle align if taken to geographic (i) north and (ii) south pole?          ( 1)

Question 5. 

The instantaneous voltage from an A.C. source is given by E=300 sin 314t . What is the R.M.S. voltage of the source?                                            ( 1)

Question 6. 

Compare the radii of two nuclei with mass number 1 and 27 respectively.                                      ( 1)

Question 7. 

How does energy gap in an intrinsic semiconductor vary, when doped with a pentavalent impurity.                                                   ( 1)

Question 8. 

If the temperature of good conductor increases, how does the relaxation time of electrons in the conductor change.                       ( 1)

Question 9. 

Draw a labelled ray diagram showing the formation of image using a Newtonian type reflecting telescope.                                         ( 2)

Question 10. 

The output voltage of an ideal transformer, connected to a 240 V A.C. is 24 V. When transformer is used to light a bulb with rating 24 V , 24 W, calculate the current in the primary coil of the circuit.                                                    ( 2)

Question 11. 

Can magnetic field set a resting electron into motion?                           ( 2)

Question 12. 

You are given two nuclei ₃X7 and ₃Y4. Are they isotopes of same element? State the reason . Which one of the two nuclei is likely to be more stable.                                                            ( 2)

Question 13. 

A heater coil is rated 100 W , 200 V. It is cut into two identical parts. Both parts are connected together in parallel , to the same source of 200 V. Calculate the energy liberated per second in new combination.                                                       ( 2)

Question 14. 

A charge q moving in a straight line is accelerated by potential difference V. It enters uniform magnetic field B perpendicular to its path . Deduce in terms of V an expression for the radius of circular path in which it travels.                         ( 2)

Question 15. 

State the reason for the following observations recorded from the surface of the moon: ( 2)

(i) sky appears dark

(ii) rainbow is never formed.

Question 16. 

Write any three characteristics , a ferromagnetic substance should posses , if it is to be used to make a permanent magnet. Give one example of such material.                  ( 2)

Question 17. 

The value of ground state of hydrogen atom is -13.6 eV.

(i) What does the negative sign signify.

(ii) how much energy is required to take an electron in this atom from ground state to the first exited state.               ( 2)

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